This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for passerines
Lynx Edicions and BirdLife International will soon publish the second volume of the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.
The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.
Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.
The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 2 of the checklist (for passerines) will begin to be incorporated into the 2016 Red List update, with the remainder to be incorporated into subsequent Red List updates.
Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.
Creamy-breasted Canastero Asthenes dorbignyi is being split into A. dorbignyi, A. huancavelicae, A. usheri and A. arequipae, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, A. dorbignyi was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. A. dorbignyi (as now defined following the taxonomic change) is found in arid montane, scrubby habitats in the Andes of central, south and south-west Bolivia and north-west Argentina (Remsen 2016). A. arequipae is found in arid scrub habitats on the western slopes of the Andes in south-west Peru (additionally incorporating an undescribed taxon from Ayacucho), northern Chile and west Bolivia. Both species can tolerate a degree of habitat destruction and, while the population size has not been quantified for either species, neither is thought to have a small enough population size to approach the threshold for Vulnerable. Therefore, it is proposed that both species be listed as Least Concern.
A. huancavelicae and A. usheri are found in arid valleys with scattered thorny bush (BirdLife International 2000). A. huancavelicae occurs in the Andes of west and central Peru (locally in Ancash; an undescribed taxon which may represent a separate species), as well as Huancavelica and Ayacucho, while A. usheri is rare to locally common in Ayacucho and Apurímac (BirdLife International 2000). These two species have previously been jointly assessed as A. huancavelicae by BirdLife and that taxon was deemed to be Vulnerable under criterion C1 (BirdLife International 2000) owing to a small combined population size estimated to be 2,500-10,000 mature individuals which was likely to be declining as a result of burning and grazing of its habitat and indirect habitat damage caused by a change in humidity resulting from deforestation of adjacent areas (BirdLife International 2000). These threats have likely continued since that previous assessment, but it is uncertain whether they are sufficient for a 10% population decrease over the past 3 generations (11-12 years).
Both species are tentatively suspected to remain within the range of 2,500-10,000 mature individuals, although probably now towards the lower end of that range. Any further information regarding population estimates would be very welcome. The distribution of A. usheri suggests that it is found in only 1 subpopulation and so would then warrant listing as Vulnerable under criterion C2a(ii). The presence of the undescribed taxon in Ancash within A. huancavelicae means this species would not qualify as Vulnerable under criterion C2a(ii). We request any further information regarding population declines in this species to see whether it still would qualify as Vulnerable under criterion C1.
BirdLife International 2000. Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International.
Remsen, J.V., Jr 2016. Creamy-breasted Canastero (Asthenes dorbignyi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/56504 on 28 September 2016).
Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. 2010. Quantitative criteria for species delimitation. Ibis 152: 724–746.